DURATION OF EMBRYO DEVELOPMENT. 35 



SECOND DAY. 



FIRST SERIES. 



SECOND SERIES. 



THIRD SERIES. 



O'CLOCK 



7-8.0. 10-11 Meso- 

 blastic So- 

 mites 

 (weak mus- 

 cular move- 

 ment). 



10.0. 11-12 Meso- 

 blastic So- 

 mites. 



12.0. 13 Mesoblastic 

 Somites. 



2.0. 14 Mesoblastic 

 Somites. 



G.O. Mouth and 

 first gill- 

 slit perfor- 

 ated as 

 fine open- 

 ings. 



O'CLOCK 



8.30. 14 Mesoblastic 

 Somites. 



11-1. 



2.30. 



5.30. 



Perforation 

 of mouth 

 and first 

 gill-slit 

 pr e p ar e d 

 for. 



Mouth and 

 first gill- 

 slit perfor- 

 ated with 

 very fine 

 opening. 



Both open- 

 ings still 

 very small. 



o CLOCK 



